std: Fill in all missing imports

Fallout from the previous commits

src/libstd/io/extensions.rs

@@ -16,6 +16,7 @@
 use iter::Iterator;
 use option::Option;
 use io::Reader;
+use vec::OwnedVector;
 
 /// An iterator that reads a single byte on each iteration,
 /// until `.read_byte()` returns `None`.

src/libstd/io/net/ip.rs

@@ -10,9 +10,11 @@
 
 use container::Container;
 use from_str::FromStr;
+use iter::Iterator;
 use option::{Option, None, Some};
+use str::StrSlice;
 use to_str::ToStr;
-use vec::{MutableCloneableVector, ImmutableVector};
+use vec::{MutableCloneableVector, ImmutableVector, MutableVector};
 
 pub type Port = u16;
 

src/libstd/io/stdio.rs

@@ -26,6 +26,7 @@ out.write(bytes!("Hello, world!"));
 
 */
 
+use container::Container;
 use fmt;
 use io::buffered::LineBufferedWriter;
 use io::{Reader, Writer, io_error, IoError, OtherIoError,
@@ -37,7 +38,9 @@ use result::{Ok, Err};
 use rt::local::Local;
 use rt::rtio::{DontClose, IoFactory, LocalIo, RtioFileStream, RtioTTY};
 use rt::task::Task;
+use str::StrSlice;
 use util;
+use vec::ImmutableVector;
 
 // And so begins the tale of acquiring a uv handle to a stdio stream on all
 // platforms in all situations. Our story begins by splitting the world into two